The Isabella was a three-masted wooden barque built at South Town, Yarmouth, in 1826, 89.7 feet long with a beam of 24 feet. She arrived in Hobart from London in February 1837 with a cargo of sheep, called at Launceston, and on 21 March sailed from George Town for the new settlement at Adelaide. On 1 April 1837 her master, Captain John Hart – later a Premier of South Australia – mistook Cape Nelson for Lady Julia Percy Island at the head of Portland Bay in poor visibility and ran into the eastern cliffs of the cape. All 25 people aboard got away in the longboats and were taken in by the Hentys at Portland, whose settlement was then barely three years old. She was the first recorded wreck at Cape Nelson and is one of the oldest located wrecks in Victoria, five years older than the Children at Childers Cove and contemporary with the Thistle at Port Fairy.

After nearly two centuries in the surge zone under a basalt cliff, the Isabella is an archaeological site rather than a wreck to look at. The Scuba Doctor lists it in about 10 m for Open Water divers, sheltered on the eastern side of the cape, and notes that the GPS mark may vary and the sounder should be used to find the site; what is there is ballast, iron fittings and fastenings in the boulder gutters at the cliff base, with the basalt reef around it carrying the kelp, sponges, crayfish and reef fish of Cape Nelson generally – wrasse, morwong, sweep, leatherjackets, catsharks. Devils Kitchen, a named reef site, is 325 m to the south. It is a dive for people interested in the earliest years of Victorian settlement, best combined with Flat Rock and the lighthouse reefs on a calm day out of Portland Harbour, and it is a protected historic shipwreck on the Discovery Coast section of the Historic Shipwreck Trail; nothing may be disturbed.

Boats launch at the Portland Harbour ramps on Lee Breakwater Road (North Ramp and South Ramp), both with trailer parking, inside the harbour breakwaters. From the harbour run south-west around Point Danger and along the eastern side of Cape Nelson about 13 km, 30 minutes, to the cliffs north of Devils Kitchen; the Scuba Doctor advises using the sounder to locate the wreck because GPS marks vary. Anchor on sand below the cliffs.

Cape Nelson Lighthouse tide and swell forecasts apply. Portland SCUBA in town supplies air; no dive charter operates from Portland.

The site is under the eastern cliffs of Cape Nelson, sheltered from westerlies by the cape but open to the south and east and subject to backwash off the cliffs. The Scuba Doctor's advice is a low swell with light north or northerly winds. Southerly swell over about 1 m and any easterly weather make the cliff base dangerous for a boat and pointless for a diver.

The Bonney Upwelling can bring cold green water in summer; autumn is clearest.

Anchor on sand below the cliffs in 8–10 m, descend and search the boulder gutters at the cliff base for ballast, iron fittings and any timber remnants, working along the shore in both directions from the mark. Treat it as a reef dive with an archaeological search; turn at half gas and return to the anchor.

No dedicated dive charter operates from Portland. Portland SCUBA (PADI centre) runs courses and occasional day trips; local fishing charters take divers by arrangement; Portland dive club members use private boats. Warrnambool Diving visits occasionally.

Rarely visited; of interest mainly to wreck historians.